Deep tillage points such as shown in U.S. Pat. Nos. 5,437,337 and 5,540,288 have been designed to leave soil surface relatively level while still achieving substantial sub-soil fracturing. In commonly assigned U.S. Pat. No. 6,443,237 a central body or point with opposed wings extend downwardly and laterally is shown. The upper surface of each of the wings forms an upward angle in the rearward direction of approximately 15 degrees with the horizontal. The point is slid onto a lower mounting portion of a ripper shank, and a bolt is inserted through a hole in the shank and a set of slots in the lower rear portion of the point. The bolt, hole, and slot arrangement provides a loose connection between the shank and the point and functions primarily to retain the point when the point is out of the ground. Ground reaction forces are transferred directly from the point to the mounting portion so that the bolt is not heavily loaded during tillage operations.
Although the deep tillage points described above have reduced ground disturbance compared to many other previously available point designs, farmers continue to require lessened soil disturbance. Conservation farmers desire a relatively wide point for fracturing but still want low surface disturbance and high residue retention, particularly when operating in highly erodible land conditions. An improved point structure is necessary that provides the high fracture, high residue, low surface disturbance ripping desired by many farmers today. In addition, it is desirable to provide a point structure which reduces need for leveling and/or slot closing wheels. In point structures such as described above, lifted soil falling from the back edges of the wings it is not able to drop fully because the edges are located along side the shank. Soil flow beside the shank creates a substantial amount of wear on the rear of the shank as the soil tries to drop back towards the ripper slot. Also, surface disturbance is created by soil flowing aggressively around the back edge of the ripper shank towards the ripper slot.
In many point structures, the thin hardware attaching surfaces or walls at the rear of the point are the limiting factor in attempts to extend point life. The carbides used to extend the wear life often deposit in the thin section around the attaching bolt slot and result in brittleness and part breakage. Therefore, the thin walls were the limiting factor in the amount of carbides that could be used without risk of cracking.
Farmers often desire to simply leave a slot in the soil for better moisture absorption and air infiltration. In such situations, a wingless ripper point for inter-row ripping in standing crops is necessary.